ESXi hosts store all files necessary for virtual machine operation in a VMware Virtual Machine File System (VMFS). Proper capacity management is critical as this file system is required for any operations related to virtual machines.
This document outlines potential issues related to a VMFS file system becoming full.
All VMFS files systems (vmfs2, vmfs3, vmfs5, vmfs6) must retain a certain level of free space to ensure that virtual machines functions properly. Ensure that these capacity thresholds are met:
200 Megabyte Capacity | VMware suggests 200 MB as the threshold where ESXi system administrators should take action to resolve capacity issues. VMFS volumes vary widely in size and it is impossible to define a precise percentage, but the risk of unexpected problems becomes greater at this capacity. |
100 Megabyte Remaining | 100 MB is defined as a critical threshold at which ESXi system administrators must take immediate action to correct the issue. |
For more information, see Increase VMFS Datastore Capacity, and Unable to grow or expand a VMFS volume or datastore.
This is a list of some potential issues that may affect virtual machines residing on a VMFS that is full:
Virtual machine startup failure | ESXi hosts are able to provide more RAM space than is available in the total physical RAM installed in the server. This is termed overcommitment. ESXi hosts create a .vswp files for any virtual machine that has allocated memory greater than the physical RAM that is available to the virtual machine. The <VMName>.vswp file is created when the virtual machine is started. Without sufficient space, this file cannot be created, and the virtual machine is unable to start. |
VMotion failures | ESXi hosts that are in a cluster that have VMware HA/DRS enabled may encounter failures when VMotion attempts to move a virtual machine from one host to another. It is possible for this failure to occur when it may not be immediately identified as a failure because VMware DRS can be configured to VMotion virtual machines without interaction from an administrator. |
Snapshot creation/commit | When a snapshot is taken or committed to the virtual machine, data is written to the VMFS file system. If the file system is unable to accommodate the additional data, the snapshot does not grow, does not get written, or is not committed. |
Poor performance |
File copy, Note: Journaling filesystems (like VMFS) are generally capable of maintaining proper performance when at nearly full capacity. However, the probability of performance problems is greatly increased when the filesystem becomes 100% full. |
Unpredictability | It is difficult to predict precisely how a full filesystem may create issues because VMFS is a core element of the ESXi host. To ensure more efficient troubleshooting and system operation, keep VMFS below the thresholds defined above. |
Note: This is not a comprehensive list of all possible issues, but it identifies important issues that have been reported in past instances of a full VMFS file system.
When a VMFS is full, there are several courses of action: